Drive unit for floor treating machines



Dec.' 3l,` 1957 w. E. HoLT 2,817,977

DRIVE UNIT FOR FLOOR TREATING MACHINES Filed June 10, 1953 INVENTOR ATTORNEY United States Patent F DRIVE UNIT FOR FLOOR TREATING MACHINES William E. Holt, Oakland, Calif.

Application June 10, 1953, Serial No. 360,657

3 Claims. (Cl. 74-421) which the drive parts are immersed. The oor surface treating element is detachably connected to the rotatable vhousing and driven thereby.

The rotatable housing type drive unit disclosed in said Aprior Patent No. 2,468,929 is particularly designed forvand especially useful in heavy duty door machines. However its relatively numerous parts and dynamically balanced housing make it too heavy and expensive to manufacture for use in low cost light weight floor surfacing machines.

The object of the present invention is the provision of an improved construction of a speed reduction drive unit for oor treating machines of the character described which is characterized by its light weight, relatively few parts, low cost of manufacture, and ease of assembly and disassembly.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specic objects attained by its use, reference should be had to the accompanying drawing and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

Of the drawing:

Fig. 1 is a partly diagrammatic elevation of a portion of a portable floor maintenance machine adapted to be constructed in accordance with the invention;

Fig. 2 is a horizontal section through the drive unit taken on the line 2 2 of Fig. 3;

Fig. 3 is a vertical section through the drive unit; and

Fig. 4 is a bottom View of the drive unit.

In the oor maintenance machine illustrated in Fig. l, an annular downwardly flared base plate supports a substantially cylindrical housing 12 enclosing an electric drive motor 14. A pair of supporting wheels 16 are tiltably mounted on the rear side of the base plate lll. A socket 18 on the base plate receives a hollow handle 20 by which the machine is directed by the operator. The handle serves as a conduit for electrical connections 22 to the motor.

The drive motor 14 is arranged with its drive shaft 24 vertical and extending coaxially of the base plate 10. A helical pinion gear 26 is keyed on the lower end o1 the drive shaft 24 and is operatively connected through a speed reducing drive unit enclosed by the casing 10 to a rotary oor treating element, shown for example, as a rotary brush 28, as hereinafter described.

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In accordance with the invention, the speed reducing drive unit comprises an elongated substantially elliptical housing top plate 30 having straight side edges and rounded ends and a peripheral depending flange 32 of corresponding shape, and extending downwardly to the level of the bottom of .the drive shaft. The plate has a central opening 34 through which the drive shaft 24 projects. Projecting perforated tabs 36 symmetrically arranged on opposite sides of the periphery of the plate 30 permit the plate to be rigidly secured in position within the machine base plate 10. The lowersection of the drive unit housing is formed by a substantially elliptical dish-shaped bottom plate 40 arranged with its periphery 42 registering with the plate flange 32 and connected thereto lat symmetrically spaced points by machine screws 44. A flexible gasket 45 insures a fluid tight joint between the housing sections.

A short stationary vertical shaft 46 is positioned in an opening 48 in the top plate 30 and a recess 50 in a boss 52 in the bottom plate 40, with a double idler gear unit rotatably mounted on the shaft 46. The double idler gear unit consists of a lower helical gear 54 having an upper tubular extension 56 on which an oppositely pitched helical gear 58 of substantially larger diameter is keyed. A sleeve bearing 60 is press fitted into the gear 54 and extension 56 and rotatably contacts with the shaft 46. Bronze washers 62 are arranged on the shaft 46 between the ends of the gear 54 and extension 56 and the boss 52 and top plate 30 respectively.

The housing bottom plate 40 has a central opening delined by a depending sleeve 70 positioned concentrically with the drive shaft 24. A bronze sleeve bearing 72 is press fitted into the sleeve 70.` An auxiliary drive shaft 74 is rotatably mounted in the bearing 72 coaxially of the -drive shaft 24 and has shouldered end portions 76 and 78 projecting respectively above and below bronze washers Sil positioned at opposite ends of the sleeve 70. A helical gear 82 is detachably mounted on the threaded reduced upper end of the shaft 74 with its lower side engaging the shoulder 76, and arranged to mesh with the gear 54. The gear 82 is of a diameter approximating the minor axis dimension of the elliptical housing, so that this space is advantageously substantially fully occupied.

With the described gear and shaft arrangement and the housing containing a body of lubricant, such as grease or lubricating oil, the electric motor 14 is energized to drive the high speed shaft 24, and, through the speed reducing gears 26, 58, 54 and 82, the low speed auxiliary drive shaft 74. The auxiliary drive shaft 74 carries a rotatable cup-shaped brush support bracket 84 which is threaded on the reduced lower end of the shaft 74 with its inner bottom surface in contact with the shaft shoulder 78 and washer 80. The bracket 84 extends upwardly around the sleeve 70 in spaced relation therewith and with its upper end subjacent the underside of the housing bot tom plate 40. The space between the bracket and sleeve is rendered leakproof by an annular inverted U-shaped flexible gasket 86 seated on an annular shoulder 88 on the bracket and contacting with the sleeve 70. Angularly spaced external lugs 90 are symmetrically arranged on the lower portion of the bracket 84 and adapted to detachably support the rotary brush 28 by bayonet type joints in a well known manner.

The described speed reducing drive parts may be easily and quickly assembled in the drive housing and the housing filled with lubricant to the desired level. The drive unit is then connected through the tabs 36 to the base plate 10 with the pinion gear 26 meshing with the idler gear 58. The rotary surface treating element 28 is then mounted on the bracket 84 and the machine is ready for use.

The described drive unit is light in weight and of low cost, and yet highly effective as a speed reducing drive unit for machines of the character described. The leak-proef construction prevents the leakage of lubricant onto the surface being treated, as well as the entrance of foreign material into the drive unit.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form of the invention now known to me, those skilled in the art will understand that changes may be made in the form of apparatus disclosed without departing from the spirit of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of other features.

What is claimed is:

1. In a surface treating machine having a motor driven vertical main drive shaft, a speed reducing drive unit comprising a stationary drive unit housing of substantially elliptical horizontal cross-section adapted to contain a body of lubricant and into which said drive shaft projects, a vertically extending sleeve depending from the otherwise imperforate bottom of said stationary housing `coaxially of said main drive shaft, a sleeve bearing fixed in said sleeve, an auxiliary drive shaft rotatably mounted in said sleeve bearing, a gear on the upper end of said auxiliary drive shaft having a diameter approximating the minor axis dimension of said elliptical housing and operatively connected to said main drive shaft, a cup-shaped bracket carried yby said auxiliary drive shaft and surrounding said sleeve over a major portion of its length in spaced relation therewith, and sealing means seated in the sleeve-surrounding portion of said bracket and in contact with the outer surface of said sleeve yfor preventing the upward passage of lubricant through the annular space between said bracket and sleeve.

2. In a surface treating machine having a motor driven vertical main drive shaft, a speed reducing drive unit comprising a stationary sectional drive unit housing of sub stantially elliptical horizontal cross-section adapted to contain a body of lubricant and into which said drive shaft projects, a pinion gear on said shaft, a vertical stationary shaft mounted in said housing, a sleeve bearing surrounding said stationary shaft, a double idler gear mounted on said sleeve bearing and engaging said pinion gear, a verti cally extending sleeve depending from the otherwise imperforate bottom of said stationary housing coaxially of said main drive shaft, a sleeve bearing fixed in said sleeve, an auxiliary drive shaft rotatably mounted in said sleeve bearing, a gear on the upper end of said auxiliary drive shaft having a diameter approximating the minor axis dimension of said elliptical housing and operatively connected `to said double idler gear, and a cup-shaped bracket of circular horizontal cross-section carried by said auxiliary drive shaft and surrounding said sleeve in spaced relation therewith.

3. In a surface treating machine having a motor driven vertical main drive shaft, a speed reducing drive unit com` prising a stationary sectional drive unit housing of substantially elliptical horizontal cross-section adapted to contain a body of lubricant and into which said drive shaft projects, a pinion gear on said shaft, a vertical stationary shaft mounted in said housing, a sleeve bearing surrounding said stationary shaft, a double idler gea. mounted on said sleeve bearing and engaging said pinion gear, a vertically extending sleeve depending from the bottom of said stationary housing coaxially of said main drive shaft, a sleeve bearing fixed in said sleeve, an auxiliary drive shaft rotatably mounted in said sleeve bearing, a gear on the upper end of said auxiliary drive shaft having a diameter approximating the minor axis dimension of said elliptical housing and operatively connected to said double idler gear, a cup-shaped bracket carried by said auxiliary drive shaft and surrounding said sleeve over a major portion of its length in spaced relation therewith, and sealing means seated in the sleeve-surrounding portion of said bracket and in contact with .the outer surface of said sleeve for preventing the upward passage of lubricant through the annular space between said bracket and sleeve.

References Cited in the tile of this patent UNITED STATES PATENTS 1,011,954 Herr Dec. 19, 1911 2,026,006 Wennerstrom Dec. 3l, 1935 2,221,315 Okun Nov. 12, 1940 2,468,929 Holt et al. May 3, 1949 

